This invention relates to an apparatus for sucking an article like a workpiece to be cut by a woodworking machine by negative pressure.
The workpiece which is to be cut by a woodworking machine is held by an apparatus for sucking by negative pressure as shown in FIGS. 1-2 in general.
In FIGS. 1-2, the apparatus has a plane shaped table 1 the inside of which is provided with a negative pressure recess 2. This recess 2 is connected with a tube 3 which is attached to one side wall 1A of the table 1. A pointed end of the tube 3 is connected with a vacuum pump (not shown) or a blower (not shown) which sucks the air in the recess 2.
The top wall 1B of the table 1 is provided with a big opening 4 and this opening 4 is covered with a plate 5 which is mounted on the top wall 1B. The plate 5 is provided with a opening 6 which is connected with the opening 4 of the top wall 1B.
According to the above construction, a workpiece 7 is mounted on the top surface of the plate 5 in such a condition that the workpiece 7 covers the opening 6 of the plate, then the vacuum pump or the blower is operated, so that the air in the recess 2 is drawn. As a result, one part of the workpiece 7, which part is facing the opening 6 is sucked below and the workpiece 7 is held on the plate 5.
It is possible to adhere a seal member on the plate 5 in order to increase the airtightness and the coefficient of friction between the plate 5 and the workpiece 7.
However, there are many sizes and shapes of workpieces 7, so that it is necessary to provide many kinds of plates 5 corresponding to many kinds of workpieces 7. As a result, much money and much time are necessary to manufacture many plates 5, and wide space is necessary to keep the plates 5.
Moreover, it is difficult to manufacture many kinds of workpieces 7. Furthermore, the shapes of the plates 5 are changed while the long preservation, so that the quality of the plate 5 becomes worse.
If the workpiece 7 is changed, it is necessary to change the old plate 5 into new plate 5 corresponding to the new workpiece 7.
In case of using a seal member on the plate 5, it is necessary to maintain the seal member, and the measure of the workpiece varies according to the thickness of the seal member.